Southern IPM blog posts

Funded by USDA National Institute of Food and Agriculture

The Southern Region IPM Center is located at North Carolina State University, 1730 Varsity Drive, Suite 110, Raleigh, NC 27606, and is sponsored by the United States Department of Agriculture, National Institute of Food and Agriculture.

The Florida citrus industry knew citrus greening disease could come but was not well prepared to tackle the disease once it appeared.

So says Bob Shatters, a research molecular biologist with USDA’s Agricultural Research Service in Fort Pierce, Fla., who added the big lesson from the devastating disease is to keep an eye out for what’s occurring internationally and be willing to address issues before major problems occur.

“I know that’s easier said than done because there are always problems here, but when this one came, there was a lot of scientific catch up that had to be done,” said Shatters in the keynote address to the American Peanut Research and Education Society annual meeting in Clearwater, Fla., July 13.

The war against citrus greening goes back to 2005 when Florida’s citrus industry was assaulted by the insect Asian citrus psyllids, the vector for the bacteria huanglongbing (or HLB) that attacks the trees and causes citrus greening.

Shatters called citrus greening “a perfect storm” disease because it has a long latency period of more than two years before symptoms are visible on trees. “Bacterium is internal (in the phloem) and therefore chemical delivery is difficult,” Shatters explained. In addition, the bacteria can’t be cultured in the lab which presents challenges.

Shatters said 80 to 90 percent of Florida is either infected or is going to be infected by citrus greening with some in the industry saying 100 percent of the state’s citrus crop could well be infected.

The average per tree reduction is about 40 percent compared to the production of a healthy tree. “That alone put many folks out of business,” Shatters said.

On top of that, management costs to control the disease have doubled. “You have half the production coming out of your trees, but you have doubled your costs,” he said.

Mathematical and epidemiological models predict that by 2019, the Florida citrus industry will no longer be commercially viable, the researcher cautions.

“We are at a tipping point. Promising research is coming out. The idea is to implement this research in stages so that we can get the growers to maintain productivity while better and better strategies come out. We are looking at strategies to slow the rate of the disease progression,” Shatters said.